Originally posted by Dendarah
That concept only works if the universe is made up of four dimensions, time being the fourth. In the theory of the fourth dimension being time that would mean that it is infinite in both direction, past and future; therefore, if given the right velocity to be able to alter the fourth dimension at the right moment you could theoretically be sent to the future. Only if time is a dimension though and both the past and future go one forever. Without the fourth dimension you could never be able to go back in time or do anothing time travel related.:rolly2:
Thats true, but if you were to travel backwards or forwards in time, then you have to consider Einsteins Theory of Special Relativity, because time itself is altered by relativity.
Time as a fourth dimension is an accepted theory, this is due to the proof of time dilation (For example, the atomic clock experiment, twin paradox theory). So if time is to be considered as a fourth dimension, then really relativity must also be considered in the issue of time travel. Anybody who has seen the episode "A Matter of Time" will remember the increasing rate of time dilation as the wormhole remained open on Earth and on P3W-451. A few seconds on the planet was hours on Earth. In another example, the twin paradox, a twin baby is sent in a ship away from the earth while its other twin remains on earth. As the twin on the ship reaches the age of 40
relative to his frame of reference (that is clocks and ageing processes), his twin on Earth reaches the age of 60. And the thought processes are vice versa. According to each twin, the other will age more slowly. Remembering that the theory of Special relativity
only accounts for internal frames of reference they cannot both be correct. it is however, proven that the twin on the ship has aged more slowly, according to relative velocities. at faster velocities, time elapses more slowly, and so the twin on the ship will be younger in proportion to the time on earth and velocities.
Still with me? Don't worry I swear there is a point.....
In reality, Time dilation suggests it maybe possible to travel to other stars in our lifetime. However, suppose you were to travel to a star 100 light years away at 0.999 c ('c' being the constant speed of light), relative to earth. At this speed, just over 100 years will have elapsed according to an observer on earth. However, the person on the ship will have only observed 4. something years, (this is actually the numbers from a textbook, not my bodgy maths). And so it follow that, theoretically, you could travel to a star and back again, (if travel at 0.999c was possible) but centuries would have passed. Therefore, it is possible to travel to the future, but not, the past.
Even in a show like stargate, whereby artificial wormholes completely discard all relative motion and time, time travel is difficult to comprehend, as to the above theories and examples.
My theory is that the gate establishes a wormhole with a velocity high enough to dilate time almost to a standstill. The wormhole dilates time for the travellors, and then, once disengaged, would provide a snap-back effect, thus eliminating the time lapse on earth.
And also (sorry still rambling), Leprykawn, I have a question! If the big bang occurred at a point in time, then wouldn't that discount time as the fourth dimension, therefore making it a universal constant, which couldn't be constant, because of the proof of time dilation?
Sorry if i lost you.
Another thing as well. I said above in my poor attempt at an explanation that time travel can only go into the future not the past. Recently (last few years?) an experiment was conducted by a team of scientists at princeton, and they claimed they had, using lasers passing through cold caesium, produced a group velocity that was 300 times the speed of light. The effect of this is so dramatic that the group velocity becomes negative! This would result in time running backwards, and so there you go, time travel into the past.....